Elastic yarn



Dec, 17, 1935. B, H FOSTER 2,024,155

ELASTIG YARN Filed Sept. 14, 1932 INVENTOR Patentedl Dec. 17', 1935 UNITED STATES 2,024,155 ELAsTIc YARN v Boutwell H. Foster, Maplewood, N. J., assignor, by mesne assignments, to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application september 14, 1932, serial No. 63:100A

1 claim. (cl. 11n-57) This invention relates to an elastic yarn.

Until recently it has not been possible to manufacture elastic yarn in sizes small enough to permit its use in commercial knitting machines.

5 Such small knittable yarns are now being produced, butin order to provide a balanced yarn free from kinking, they have been provided with a double fibre covering or wrapping onthe elastic core, the coverings being helically wrapped in opposite directions. This double Wrapping of course increases the diameter, weight and cost for a given elastic core as compared with a single wrap, andfor a given core reduces the yardage per pound of nished yarn.

l5 An object of the present invention is to provide a knittable single wrap elastic yarn which is balanced and free from kinking.

Another object is to provide a knittable elastic yarn which for any given gauge is softer and more pliable than yarns of the same gauge made by previous processes.

Another object is to decrease the cost of making suchelastic yarn.

Another object is to increase the yardage obtained per pound of finished knittable yarn for any given size of elastic core.

A further object is to produce a smooth elastic yarn of finer gauge than has heretofore been possible.

A still further object is to simplify the making of small diameter elastic yarn.

The invention broadly consists in twisting a ne gauge elastic core in one direction, feeding the core forwardly under tension, and helically wrapping a single brous covering on the core in an opposite direction. It further consists in the product so obtained.

For a complete understanding of the nature and objects of the invention, reference is had to the accompanying specification and drawing, in

which latter:

The gure is an enlarged view showing a piece of the elasticyarn of the invention, with a part of the cover broken away.

Any suitable elastic core of rubber or rubberlike material may be employed in carrying out the invention, but it is preferred to employ a rubber core made in accordance with the patent to Hopkinson and Gibbons No. 1,545,257, granted July '7, 1925. Rubber cores made directly from rubbervlatex by the process disclosed in this patent lor other processes are grainless, and have much greater resistance to tearing, Also, the thread is of uniform cross section and can be made round, which is of advantage when it is to be 5' wrapped with a brous covering. Moreover, since the rubber thread made according to this patent has no'ragged or irregular surfaces, such as are frequently present in cut rubber threads, the liabilityto tear or break is also greatly reduced 10 by reason of this fact. Such thread has also been l found to have exceptional resistance to air and heat ageing, etc. Preferably,4 the latex used in making the thread is treated to remove non-rub-` ber constituents. f 15 The cores may be made from rubberlatex `suitably compounded to further increasetheir ageing qualities and to permit vulcanization at moderate temperatures or rapid vulcanization "at higher temperatures, and in general to impart ,20

to the rubber any desired characteristics for the purpose in mind, or the cores may be made from a compounded and vulcanized latex.

The brous covering to be applied in carrying out the invention may be of any suitable ma- 25 terial, such as cotton, linen, silk, rayon, wool, etc., or combinations of two or more of these. It may be in various forms and may consist of one or more endsl of yarn or plied yarn depending upon the service requirements -of the article to 30 be made from the nished yarn.

An unwrapped rubber thread o1' good quality has great extensibility, while an elastic yarn suitable for knitting should have only a somewhat limited predetermined stretch, hence in the 35 manufacture of such yarn the elastic core is maintained under sufficient tension during its covering with brous material to produce a iinished yarn having the desired limited stretch. In carrying out the invention, the elastic core I is fed under proper tension and with a twist imparted to it in one direction, while the covering yarn 2 is helically wrapped around the elastic core inAan opposite direction. Any suit- 45 able apparatus may be used for producing the v twist in the elastic core and wrapping the covering yarn upon it. For instance, a machine now in use for placing two oppositely wound brous coverings on an untwisted elastic core may be tions on the core, the elastic core itself may be disposed on the rst of these spindles instead of a rst covering yarn, and a twist imparted to the core by feeding it from the rotating spindle through the rotating traveller ordinarily employed for guiding the rst helical wrapping of yarn.

-the elastic core and as it travels through and beyond the second spindle, the single helical wrapping of covering yarn of the present invention may be applied from the position in which ordinarily the second wrapping of yarn would be applied, and in an opposite direction to the twist of the core.

The tension and number of twists pei'` inch of the elastic core and the pitch o f wrap and number of wraps per inch of the covering yarn, will, of course, be varied depending upon the size of the elastic core, the nature and form of the covering yarn and other variables, as apparent to those skilled in the art. These variables may be varied so as to produce a single covered elastic yarn which is balanced and free'from tendency to kink, that is, one in which the helically Wrapped covering substantially exactly counteracts the torque of the twisted elastic core. Preferably, however, there should be at least fifteen turns per inch in the tensioned wrapped twisted core.

As illustrating the invention, the following ta` bles give the structure characteristics of nine specimens of elastic yarn made according to the invention. In considering the data in these tables, it is to be noted that the data were compiled from measurements on a yard length or on a fraction of a pound of the elastic yarn, and consequently any slight error in measurement thereof may have been multiplied in the figures given in the tables. Nevertheless, the data are accurate within ythe tolerances recognized in the trade. 'I'he gures given in the tables are therefore to be taken as illustrative and not limiting.

Table I Designation A B C l. Gauge of bare circular rubber core, relaxed and untwisted..- 010l y .010" 010 2. Yards of elastic yarn per poundnormal condition. 20, 200 6, 060 19, 150 3. Elongation of elastic yarnincrease over normal length on stretching to limit. 110% 100% 4. Material of covering 1-2 ply 4-100/1 1-2 ply 13/15 cotton 13/15 Cheney silk silk 5. Wraps of covering per inch of Y elastic yarn 98. 0 L 63. 4 L 90. 6 L 6. Twist in rubber core per inch of elastic yarn 77. 46 R 53. 73 R 58. 7 R 7. In one yard of normal elasticyarn-the inches of bare rubber relaxed 14 20. 25 15. 25 8. In one yard ci normal elastic yani the weight in grams a. Bare rubber .0172 .0252 .0185 b. Both rubber and covering. 0224 0745 0230 9. Percent by weight of rubber core 76.8 33. 8 80. 5 l0. Percent by weight of covering.. 21.2 A 66. 2 19. 5 vl1. Yardage oi one pound oi barc v rubber core-relaxed.' 10, 200 l0. 100 10I 400 12. Yardage of relaxed bare rubber in one pound of elastic yarn. 7, 850 3, 410 8, 13. Gauge of elastic yarn 00725" 01475" 00675 Table 11 inesignmioii4 D E vF 1. Gauge oi bare circular rubber 5 core, relaxed and untwisted... 010' 010' 008' 2. Yards of elastic yarn per pound- .normal condition..."l 19,700 16,500 21400 y3. Elongation of elastic yam-inf crease over normal length on stretching to limit 110% 110% 145% 4. Material ot covering 1-2 ply 2-2 ply 1-3 Igly l() 13/15 silk 13/15 silk 13/15 silk 5. Wraps of covering per inch of elastic yarn 97. 6 L 93 L 121. 9 L 6. Twist in rubber core per inch of elastic yarn 55 R 63 R 75.15 R 7. In one yard of normal elastic yam-the inches of bare rub- 15 ber-relaxed 15.625 15 19.125' 8. In one yard of normal elastic yrn-the weight in grams o a. Bare rubber .0185 .011 .0135 b. Both rubber and covering 0234 017 .0225 9. Percent by weight of rubber core. 79.1 64.7 60% 10. Percent by weight of covering- 20. 9 35. 3 40% 20 11. Yardage of one pound o! b are rubber core-relaxed 10,650 10,650 17,850 12. Yardage ci relaxed bare rubber in one pound of elastic yarn.. 8. 550 880 l0, 825 13. Gauge of elasticyarn .00675' .0075' .007'

Table m 25 Designation G H I 1. Gauge of bare circular rubber 30 core, relaxed and untwisted..- 033" 0333" 0333" 2. Yards oi elastic yarn per pound normal condition 826 1, 1,180 3. Elongation of elastic yarn-increase over normal length on stretching to limit 105% 115% 90% 4. Materialot covering Gends 4ends 4ends cotton cotton cotton 5. Wraps of covering per inch o! elastic yarn 24.9 left 29.21eit 29.1leit 6. Twistinrubber core per inch ol f' elastic yarn 19.0right 20.4right Zrlght 7. In one yard of normal elastic yam-the inches of bare rubber relaxed 20%" 15%" 13%" 40 8. In one yard of normal elastic l yarn-the weight in grams o I i.,Barerubber y .230 .170 .1m b. Both rubber and covering- .319 27A .213 9. Percent by weight of rubber W 43 27 4L V core 5 1o. Percent by weight of covering.- 587; 56.893 tasz; 45 11. Yardage of one pound oi bare rubber core-relaxed 1, 230 l. 120 l, 149 12. Yardage of relaxed bare rubber in onepound of elastic yarn-. 516 480 451 13. Gauge of elastic yarn .0375" .031" .0315

50 'Ihe products above described in the tables were well balanced and free from kinks.

The covered yarns, as above described in the tables, are capable of being knitted in high speed commercial knitting machines of various sizes 55 up to the nest in present use, depending upon the gauge of the yarn used. For instance, the yarn E of Table II has been successfully employed in knitting on full fashioned knitting machines of 45 and 48 gauge (needles per 1% inches), 60

and it is capable of use on a 51 gauge machine. Double covered elastic yarns at present in use, even with a core of l/izsth of anA inch, cannot be practically employed on full fashioned knitting machines ner than 42 gauge. As the present 65 demand of the full fashioned knitting trade is usually for nothing liner than 45 gauge, it will be seen that the present invention not only meets but exceeds the demand. Moreover, it will be noted that in Example E, an elastic core of 70 1/iooth of an inch diameter was used, while by using a ner coresuch as 1/izsth of an inch, a finished elastic yarn of still smaller diameter l may be obtained which is therefore capable of use on even finer ,gauge knitting machines. 75

While capable of extended use, the invention is particularly applicable with elastic cores not exceeding .020 inch in diameter, lor .00031416 square inch in cross sectional area. 'I'he iinished yarn preferably should not exceed .025 inch in diameter.

While speciic embodiments ofthe invention have been described, it is obvious that it is capable of modiiication, and it is not intended that the invention should be limited otherwise than as set forth in the appended claim.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

An elastic yarn capable of being knitted, comprising a stretched elastic core of rubber twisted ask an entirety in one direction to maintain it under torque and unbalanced from said twist, and a covering yarn helically wrapped in the opposite direction in direct frictional contact with the core to provide a covering that holds the core in a stretched condition, and the twist of the cor e 1|; just suiiicient to balance the opposi Ahelical twist of the cover, whereby an knitted in a knitting machine without kinking is produced.

BOUTWELL H. FOSTER.

tely balanced elastic yarn which can be 10 

